Unconventional Truck Chassis Design with Multi-functional Cross Members 2019-01-0839
The automobile industry is spending considerable resources to develop and manufacture lightweight structural components for vehicles and hence reduce fuel consumption. In this work an unconventional structural design for truck chassis is proposed and the structure is optimized to minimize weight while satisfying several constraints. The shape of the side-rail is specified by 41 design variables. The side rails are divided into six sections each having different thicknesses for the flanges and the web (which are also considered to be design variables). The side rails are sectioned using vertical planes and location of these planes are variables. The gearbox cross-member and the intermediate cross-members are compressed-air cylinders and hence act as multi-functional components. The location of these cross members, their inner and outer radii are considered variables; however, their volume is constrained to a constant volume. Three additional cross-members are added and are modeled using beam elements. The maximum allowable bend radius for the side rails is fixed at 1000 mm to meet manufacturing limitations. Additional geometric constraints are specified by the front and rear axle locations. The geometry of the structure is created and meshed with quadrilateral shell elements using commercial FEA software, MSC.PATRAN. The cross members are attached to the side frame by multiple point constraints (MPCs). The commercial software MSC.NASTRAN is used for normal mode analysis and static analysis (for stiffness evaluation). The model is verified by comparing the frequencies for lateral bending mode, torsional bending mode and vertical bending mode with those of high-fidelity model of comparable dimensions. The design variables specifying the shape and the thickness of the components are optimized using the Particle Swarm Optimization (PSO) algorithm implemented using parallel processing considering constraints on torsional stiffness, lateral bending stiffness and vertical bending stiffness.
Shuvodeep De, Karanpreet Singh, Junhyeon Seo, Rakesh Kapania, Raymond Aguero, Erik Ostergaard, Nicholas Angelini